High-temperature rolling mill



y 0, 1966 R. B. FISCHER 3,250,104

HIGH-TEMPEBATURE ROLLING MILL Filed Nov. 15, 1962 Z Sheets-Sheet 1 INVENTOR ROLAND B. FISCHER BY WJV w; [GWWQW May 10, 1966 R. B. FISCHER 3,250,104

HIGH-TEMPERATURE ROLLING MILL Filed Nov. 13, 1962 4 2 Sheets-Sheet 2 7 I? NWWWW FIG. 4

INVENTOR. ROLAND B. FISCHER BY i 16%,

United States Patent 3,250,104 HIGH-TEMPERATURE ROLLING MILL Roland B. Fischer, Columbus, Ohio, assignor, by mesne assignments, to Battelle Development Corporation,

Columbus, Ohio, a corporation of Delaware Filed Nov. 13, 1962, Ser. No. 237,171 S Claims. (Cl. 72-201) This invention relates to rolling of metal and materials. More particularly, it relates to a method and apparatus for rolling metals and materials at or above temperatures of incandescence.

Conventionally, metals are rolled to the desired form with the metal and work rolls at room temperature or with the metal heated and the rolls merely warm. The most common rolling operation is the formation of sheet metal. This invention provides for rolling metal at elevated temperatures so that less pressure is required between the rolls and the metal. Various desirable characteristics in the metal are obtained by maintaining the metal at an elevated temperature during rolling. Although the invention has widespread use, one of its most valuable applications at the present time is in the field of laboratory metallurgical work. in the past, metallurgists have heated their specimens in an auxiliary furnace and then quickly fed the specimens into conventional warm rolls. Accurate temperature control, which is desirable and often necessary in such a process, cannot be maintained because the small specimens lose considerable heat during the transfer from the furnace to the rolling mill. Heat loss can be partly overcome by superheating the specimen or by a special setup such as placement of the furnace near the rolls. With large rolls having a good bite, heated specimens can be dropped from an overhead furnace into the rolls. One problem with such setups is that the metal, especially its surface, cools substantially when it contacts the relatively cooler rolls. For example, for thin specimens at an initial temperature of about 800 F., exit temperature (from the rolls is about 630 F. Although dependent to some extent on the width of the specimen, examples of thin flat specimens are those having a sutficiently small thickness so as to be characterized by the ability to lose temperature upon passing through rolls during hot rolling. By way of example, this would include within its scope hot-rolled carbon steel products classified as strip as opposed to those classified as bar, plate or sheet. For flat steel, the thickness at which strip can be differentiated from other products ranges from about 0.23 to about 0.25 inch when width is less than about 12 inches (see The Making, Shaping and Treating of Steel, United States Steel Corporation, Seventh Edition, 1957, p. 584). Although the above refers particularly to steel, it is known within limits recognized to those skilled in the art that a similar dimensional classification holds for other metals. For round configurations, the equivalent thin diameter would not be greater than about 1.8 inches. Whenever good temperature control and maintenance of temperature level are desired, then conventional hot mills (actually meaning warm rolls or rolling mills that handle heated specimens) are inadequate.

Another important factor is the durability of the rolls that are intended for rolling metal at high temperatures. Conventional rolling of metal at incandescent temperatures (about 1000 'F., or greater) necessitates cooling the roll surfaces so that the rolls do not acquire the temperature of the material being rolled and thus become seriously weakened. In this invention, instead of the roll surfaces being cooled, they are heated. Thus, the rolled material is maintained at, or has imparted to it, an elevated temperature. An environment is produced so that,

Patented May 10, 1966 in essence, the metal is rolled while it is heated in a furnace.

Briefly described, this invention includes a pair of rolls having a heat-resistant surface, means for heating the rolls and means for cooling the bearings of the rolls.

One advantage of this invention is that metal can be rolled at high temperature with slow deformation rates. Since temperature is controlled more precisely, the rolled products have more uniform properties, such as grain structure and tensile strength, throughout the rolled material. ner gauges of metal can be produced without the large pressures usually required to produce thin gauge material. Still another advantage of the invention is in rolling powders combining pressing and sintering into one. operation. Other advantages and features of the invention will be apparent from the following description, the drawings, and

the claims.

In the drawings:

FIG. 1 is an elevational view of a rolling mill according to this invention;

FIG. 2 is a sectional elevational view of the apparatus shown in FIG. 1 with the section taken perpendicular to the axes of the rolls at about their midpoint;

FIG. 3 is a perspective view of a bearing block used in the apparatus shown in FIG. 1; and

' FIG. 4 is a sectional view of a bearing block taken along the line 4-4 of FIG. 3.

Referring to FIGS. 1 and 2, the rolling mill 11 includes a frame 13, enclosed by side plates 15-15 and a cover plate 17. The side plates 15-15 and cover plate 17 are each attached to the frame by suitable fastening means such as bolts 19-19. A base 21 is attached to the frame 13 for supporting the mill 11.

An opening 23 is provided in each side plate 15 for insertion of the bearing blocks. 25-25 that support the stationary roller 27 and the bearing blocks 29-29 that support the adjustable roller 31. The bearing blocks 25-25 and 29-29 are provided with a guide 33 that fits into a mating groove (not shown) on each side of the opening 23 and are slidable in the opening 23. A hole 35 is centrally located in each of the bearing blocks 25-25 and 29-29 for supporting the shafts 37 and 39 of rollers 27 and 31. Referring to FIG'. 4, a channel 41 is passed through the interior of each block 25-25 and 29-29, and is provided with an inlet opening 43 and an outlet opening 45 (FIG. 3) so that a cooling liquid can be passed through the bearing blocks 25-25 and 29-29.

Each bearing block 29 is connected to an adjustment means 47 (one adjustment means 47- for each bearing block29) that permits the rolls 27 and 31 to be set closer together or farther apart by movement of bearing blocks 29-29 and consequently roll 31. Each adjustment means 47 includes a threaded shaft 49 engaged with a threaded block 51. The threaded shaft 49 has an enlarged end 53 that fits into a suitable socket, such as that formed by the two bent plates 55-55 on the bearing block 29. A large nut 57 is attached to the opposite end of shaft 49 to provide a means of turning shaft 49 for adjustment. The two adjustment means 47-47 may be coordinated by any suitable means (not shown) so that both bearing blocks 29-29 will be adjusted an equal amount. Further, spring loading means (not shown) may be provided so that roll 31 will yield to open the space between rolls 29 and 31- during periods of high pressure during a rolling operation.

Inlet coolant lines 59-59 are connected to bearing block inlet holes 43-43 and outlet coolant lines 61-61 are connected to bearing block outlet holes 45-45.

Another advantage of this invention is that thin- In FIG. 2 a specimen of metal 63 is shown being passed between the rolls 2'7 and 31. The specimen 63 first passes through an entrance passageway 65. The entrance passageway is provided with a heater such as a resistance wire 67 mounted on a support 69 made from insulating material. Each of the rolls 31 and 27 is also heated by suitable means such as resistance wires 71 mounted on a support 73 made from insulating material in the shape of a half cylinder. The space above the roll 31 and below the roll 27 is filled with insulation 75 with additional heat-resistant material added near the rolls 2'7 and 31 in the form of refractory blocks 77. The exit passageway 79 is provided with a heater such as a resistance wire 81 mounted on a support 83 made from insulating material. Although the heaters are shown as resistance wires in FIG. 2, other heating means are also suitable such as induction coils or gas burners. The provision of the heating units 67, 7171, and 81 allows the metal being rolled and the rolls 27 and 31 to be maintained at incandescent temperatures, that is, 1000 F. or greater. Not only can the metal being rolled be maintained at a selected temperature as it is taken from a furnace and supplied to the rolling mill 11, but also the metal can be heated or raised to selected temperatures. A model of the rolling mill 11 has been'successfully constructed and tried yielding the characteristics described hereinfor the rolling mill 11.

Preferably, the rolls 31 and 27 are provided with an outer layer 85 that is made from a material that has high strength at elevated temperatures. The outer layer 85 is slipped over the central core 87 of the rolls 31 and 27 and held in place by a shim 89.

The following table is a partial list of materials for use in fabrication of the outer layer 85 and shows the temperature at which plastic flow begins for each of these materials.

Beginning of Plastic In some instances, the material being rolled or the rolls themselves will require protection from oxidation. This is done by providing a special atmosphere within the rolling mill such as an inert gas or a reducing atmosphere,

hydrogen for example.

Many of the uses and advantages of the method and apparatus described herein are yet to be discovered; however, many other advantages and uses are already apparent and some have been discussed. One relatively new process in which the apparatus of this invention is highly useful is Ausformi'ng. The Ausforming process is relatively new. It has been used to obtain tensile strengths of nearly 500,000 p.s.i. in steel. The process involves the austenitizing of the steel by an interrupted quench at a temperature near the start of martensite transformation and working while the steel is still austenitic. The steel must be deformed during a limited time period before the austenite starts to transform to pearlite or bainite. After forming, the steel is quenched to form martensite and then tempered. The working of the steel in the metastable austenitic range is eifective in the development of the high-strength properties. The variables that are important for Ausforming are austenitizing temperature, deformation temperature, degree of deformation, and the time at deformation temperature. The most diflicult variable to control in a conventional austenitizing process is temperature. It is desirable to use the lowest austenitizing temperature that results in full transformation to austenite with a sufiieient degree of carbide solution. The apparatus described herein allows rolling Without excess heating since the steel does not need to be heated excessively to compensate for cooling during transfer from the furnace to the rolling mill.

' This invention is also useful in forming roll-bonded materials. Bimetals and clad sheets are commonly desired products. Unusual combinations of materials can be prepared by roll-bonding powdered metals to metal sheets. The combination of heat and pressure provide the necessary pressure and sintering in one operation.

It will be understood, of course, that, while the forms of the invention herein shown and described constitute the preferred embodiments of the invention, it is not intended herein to illustrate all the possible equivalent forms or ramifications of the invention. It will be understood that the words used are words of description rather than limitation and that various changes, such as changes in shape, relative size, and arrangement of parts may be substituted without departing from the spirit or scope of the invention herein disclosed.

What is claimed is:

1. In the method of rolling metal having a cross-section small enough to cause said metal to be characterized by the ability to lose temperature upon passing through rolls during hot rolling and having a thickness of at most about 0.250 inch when flat and a diameter of at most about 1.8 inch when round which comprises passing heated metal between rolls to reduce the thickness of-the metal, the improvement of providing a heated environment for metal entering said rolls, for said rolls, and for metal exiting from said rolls, and, by said heated environment, raising the temperature of said metal and said rolls so that said metal and said rolls are above the temperature at which said metal is soft and plastic and can be worked with lower amounts of energy throughout the pass through said rolls, said temperature being greater than at least about 1000" F. at which temperature said metals and said rolls are incandescent.

2. An apparatus for rolling thin metal at incandescent temperature comprising:

(a) a frame forming an enclosure;

(b) an entrance passageway to said enclosure;

(c) an exit passageway from said enclosure;

((1) a first pair of bearing blocks supported by said frame;

(e) a first roll rotatably mounted between and supported by said first bearing blocks;

(f) a second roll rotatably mounted between and supported by said second pair of bearing blocks having its axis parallel to the axis of said first roll;

(g) means adjacent said first and second rolls for heating said first and second rolls to temperatures greater than at least about 1000 F.;

(h) heating means provided in said entrance passageway and said exit passageway for heating the metal just prior to being rolled and just after being rolled to temperatures greater than at least about 1000 F.; and

(i) means for cooling said first and second pair of bearing blocks.

3. An apparatus for rolling metal having a cross-section small enough to cause said metal to be characterized by the ability to lose temperature upon passing through rolls during hot rolling and having a thickness of at most about 0.250 inch when flat and a diameter of at most about 1.8 inch when round at incandescent temperature according to claim 2 where the external surface of said 5 first and second rolls are covered with a material selected from the group consisting of silicon carbide, zirconium boride, titanium carbide, aluminum oxide, niobium carbide, titanium boride, tantalum carbide, chromium boride, molybdenum boride, chromium carbide, boron carbide, vanadium carbide, molybdenum carbide, and tungsten carbide.

References Cited by the Examiner 2,252,697 8/1941 Brassert 80-605 6 3/1943 De Bats 8058.1 6/1953 Porth 80-605 5/1955 Peterson 80-55.1

8/1956 Franssen 18-9 1l/ 1956 Silvasy et a1 18-9 9/1959 Heck 18-9 1/1964 Kracht 18-6 FOREIGN PATENTS 6/ 1960 France. 7/1939 Great Britain.

CHARLES W. LANHAM, Primary Examiner.

WILLIAM J. STEPHENSON, Examiner.

Dedication 3,25O,104 R0Zand B. Fischer, Columbus, Ohio. HIGH-TEMPERATURE ROLLING MILL. Patent dated May 10, 1966. Dedication filed Aug. 2, 1974, by the assignee, The Battelle Development Cowpomtz'on. Hereb dedicates to the People of the United States the entire remaining term 0 said patent.

[Official Gazette November 19, 1974.] 

1. IN THE METHOD OF ROLLING METAL HAVING A CROSS-SECTION SMALL ENOUGH TO CAUSE SAID METAL TO BE CHARACTERIZED BY THE ABILITY TO LOSE TEMPERATURE UPON PASSING THROUGH ROLLS DURING HOT ROLLING AND HAVING A THICKNESS OF AT MOST ABOUT 0.250 INCH WHEN FLAT AND A DIAMETER OF AT MOST ABOUT 1.8 INCH WHEN ROUND WHICH COMPRISES PASSING HEATED METAL BETWEEN ROLLS TO REDUCE THE THICKNESS OF THE METAL, THE IMPROVEMENT OF PROVIDING A HEATED ENVIRONMENT FOR METAL ENTERING SAID ROLLS, FOR SAID ROLLS, AND FOR METAL EXITING FROM SAID ROLLS, AND, BY SAID HEATED ENVIRONMENT, RAISING THE TEMPERATURE OF SAID METAL AND SAID ROLLS SO THAT SIAD METAL AND SAID ROLLS ARE ABOVE THE TEMPERATURE AT WHICH SAID METAL IS SOFT AND PLASTIC AND CAN BE WORKED WITH LOWER AMOUNTS OF ENERGY THROUGHOUT THE PASS THROUGH SAID ROLLS, SAID TEMPERATURE BEING GREATER THAN AT LEAST ABOUT 1000*F. AT WHICH TEMPERATURE SAID METALS AND SAID ROLLS ARE INCANDESCENT. 